blocks|key|1168503|text|我为此做了一个小的jQuery插件。原理很简单：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1168504|在容器中，插入两个内容相同的内联元素，但一个样式为非常小的.，另一个样式为非常大的A。然后，由于默认情况下有vertical-align:baseline，因此基线如下所示：|offset|length|style|CODE|1168505|+++++++%5E+%2B----%2B+%5E
+++++++%7C+%7C+%2B-%2B%7C+%7C+top
height+%7C+%7C.%7CA%7C%7C+v
+++++++%7C+%7C+%2B-%2B%7C+
+++++++v+%2B----%2B

=======================
baseline+=+top+/+height
=======================|code-block|syntax|javascript|1168506|下面是coffeescript+(JS+here)中的插件：|1168507|$+=+@jQuery+?+require+'jQuery'

detectBaseline+=+(el+=+'body')+->
++$container+=+$('<div+style="visibility:hidden;"/>')
++$smallA++++=+$('<span+style="font-size:0;">A</span>')
++$bigA++++++=+$('<span+style="font-size:999px;">A</span>')

++$container
++++.append($smallA).append($bigA)
++++.appendTo(el);
++setTimeout+(->+$container.remove()),+10

++$smallA.position().top+/+$bigA.height()

$.fn.baseline+=+->
++detectBaseline(@get(0))|1168508|然后，用以下命令抽出它：|1168509|$('body').baseline()
//+or+whatever+selector:
$('#foo').baseline()|1168510|--|1168511|试一试吧：http://bl.ocks.org/3157389|1168512|entityMap|0|LINK|mutability|MUTABLE|url|http://coffeescript.org/#try:$%2520=%2520@jQuery%2520?%2520require%2520%2527jQuery%2527%250A%250AdetectBaseline%2520=%2520%2528el%2520=%2520%2527body%2527%2529%2520-%253E%250A%2520%2520$container%2520=%2520$%2528%2527%253Cdiv%2520style=%2522visibility:hidden;%2522/%253E%2527%2529%250A%2520%2520$smallA%2520%2520%2520%2520=%2520$%2528%2527%253Cspan%2520style=%2522font-size:0;%2522%253EA%253C/span%253E%2527%2529%250A%2520%2520$bigA%2520%2520%2520%2520%2520%2520=%2520$%2528%2527%253Cspan%2520style=%2522font-size:999px;%2522%253EA%253C/span%253E%2527%2529%250A%250A%2520%2520$container%250A%2520%2520%2520%2520.append%2528$smallA%2529.append%2528$bigA%2529%250A%2520%2520%2520%2520.appendTo%2528el%2529;%250A%2520%2520setTimeout%2520%2528-%253E%2520$container.remove%2528%2529%2529,%252010%250A%250A%2520%2520$smallA.position%2528%2529.top%2520/%2520$bigA.height%2528%2529%250A%250A$.fn.baseline%2520=%2520-%253E%250A%2520%2520detectBaseline%2528@get%25280%2529%2529|1|http://bl.ocks.org/3157389^0|0|T|1|15|1|1I|N|0|0|H|7|0|0|0|0|0|0|5|Q|1|0^^$0|@$1|2|3|4|5|6|7|18|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|19|8|@$D|1A|E|1B|F|G]|$D|1C|E|1D|F|G]|$D|1E|E|1F|F|G]]|9|@]|A|$]]|$1|H|3|I|5|J|7|1G|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|1H|8|@]|9|@$D|1I|E|1J|1|1K]]|A|$]]|$1|O|3|P|5|J|7|1L|8|@]|9|@]|A|$K|L]]|$1|Q|3|R|5|6|7|1M|8|@]|9|@]|A|$]]|$1|S|3|T|5|J|7|1N|8|@]|9|@]|A|$K|L]]|$1|U|3|V|5|6|7|1O|8|@]|9|@]|A|$]]|$1|W|3|X|5|6|7|1P|8|@]|9|@$D|1Q|E|1R|1|1S]]|A|$]]|$1|Y|3|-4|5|6|7|1T|8|@]|9|@]|A|$]]]|Z|$10|$5|11|12|13|A|$14|15]]|16|$5|11|12|13|A|$14|17]]]]

<p>I made a tiny jQuery plugin for that. The principle is simple:</p>

<p>In a container, insert 2 inline elements with the same content but one styled very small <code>.</code> and the other very big <code>A</code>.
Then, since there are <code>vertical-align:baseline</code> by default, the baseline is given as follow:</p>

<pre><code>       ^ +----+ ^
       | | +-+| | top
height | |.|A|| v
       | | +-+| 
       v +----+

=======================
baseline = top / height
=======================
</code></pre>

<p>Here is the plugin in coffeescript (<a href="http://coffeescript.org/#try:$%20=%20@jQuery%20?%20require%20%27jQuery%27%0A%0AdetectBaseline%20=%20%28el%20=%20%27body%27%29%20-%3E%0A%20%20$container%20=%20$%28%27%3Cdiv%20style=%22visibility:hidden;%22/%3E%27%29%0A%20%20$smallA%20%20%20%20=%20$%28%27%3Cspan%20style=%22font-size:0;%22%3EA%3C/span%3E%27%29%0A%20%20$bigA%20%20%20%20%20%20=%20$%28%27%3Cspan%20style=%22font-size:999px;%22%3EA%3C/span%3E%27%29%0A%0A%20%20$container%0A%20%20%20%20.append%28$smallA%29.append%28$bigA%29%0A%20%20%20%20.appendTo%28el%29;%0A%20%20setTimeout%20%28-%3E%20$container.remove%28%29%29,%2010%0A%0A%20%20$smallA.position%28%29.top%20/%20$bigA.height%28%29%0A%0A$.fn.baseline%20=%20-%3E%0A%20%20detectBaseline%28@get%280%29%29" rel="noreferrer">JS here</a>):</p>

<pre><code>$ = @jQuery ? require 'jQuery'

detectBaseline = (el = 'body') -&gt;
  $container = $('&lt;div style="visibility:hidden;"/&gt;')
  $smallA    = $('&lt;span style="font-size:0;"&gt;A&lt;/span&gt;')
  $bigA      = $('&lt;span style="font-size:999px;"&gt;A&lt;/span&gt;')

  $container
    .append($smallA).append($bigA)
    .appendTo(el);
  setTimeout (-&gt; $container.remove()), 10

  $smallA.position().top / $bigA.height()

$.fn.baseline = -&gt;
  detectBaseline(@get(0))
</code></pre>

<p>then, smoke it with:</p>

<pre><code>$('body').baseline()
// or whatever selector:
$('#foo').baseline()
</code></pre>

<p>--</p>

<p>Give it a try at: <a href="http://bl.ocks.org/3157389" rel="noreferrer">http://bl.ocks.org/3157389</a></p>


blocks|key|230610|text|在Alan+Stearns+(http://blogs.adobe.com/webplatform/2014/08/13/one-weird-trick-to-baseline-align-text/)发现内联块元素改变了其他内联元素的基线对齐之后，我做了一个演示，我发现它比https://stackoverflow.com/a/11615439/67190更准确，实际上在JavaScript：http://codepen.io/georgecrawford/pen/gbaJWJ中导出值也更简单。希望它是有用的。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|230611|<div>
++<span+class="letter">T</span>
++<span+class="strut"></span>
<div>|code-block|syntax|javascript|230612|div+{
++width:+100px;
++height:+100px;
++border:+thin+black+solid;
}
.letter+{
++font-size:+100px;
++line-height:+0px;
++background-color:+#9BBCE3;
}
.strut+{
++display:+inline-block;
++height:+100px;
}|230613|entityMap|0|LINK|mutability|MUTABLE|url|http://blogs.adobe.com/webplatform/2014/08/13/one-weird-trick-to-baseline-align-text/|1|https://stackoverflow.com/a/11615439/67190|2|http://codepen.io/georgecrawford/pen/gbaJWJ^0|F|2D|0|3U|16|1|5J|17|2|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@$A|X|B|Y|1|Z]|$A|10|B|11|1|12]|$A|13|B|14|1|15]]|C|$]]|$1|D|3|E|5|F|7|16|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|F|7|17|8|@]|9|@]|C|$G|H]]|$1|K|3|-4|5|6|7|18|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]|S|$5|N|O|P|C|$Q|T]]|U|$5|N|O|P|C|$Q|V]]]]

<p>Following the discovery by Alan Stearns (<a href="http://blogs.adobe.com/webplatform/2014/08/13/one-weird-trick-to-baseline-align-text/" rel="nofollow noreferrer">http://blogs.adobe.com/webplatform/2014/08/13/one-weird-trick-to-baseline-align-text/</a>) that inline-block elements change the baseline alignment of other inline elements, I put together a demo which I found more accurate than <a href="https://stackoverflow.com/a/11615439/67190">https://stackoverflow.com/a/11615439/67190</a>, and actually more simple to derive a value in JavaScript: <a href="http://codepen.io/georgecrawford/pen/gbaJWJ" rel="nofollow noreferrer">http://codepen.io/georgecrawford/pen/gbaJWJ</a>. Hope it's useful.</p>

<pre><code>&lt;div&gt;
  &lt;span class="letter"&gt;T&lt;/span&gt;
  &lt;span class="strut"&gt;&lt;/span&gt;
&lt;div&gt;
</code></pre>

<pre><code>div {
  width: 100px;
  height: 100px;
  border: thin black solid;
}
.letter {
  font-size: 100px;
  line-height: 0px;
  background-color: #9BBCE3;
}
.strut {
  display: inline-block;
  height: 100px;
}
</code></pre>


blocks|key|230646|text|Vanilla+JS，不需要字体信息，在Chrome，Firefox和Edge上测试：|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|230647|​|230648|function+getBaselineHeight(el){
++++let+bottomY+=+el.getBoundingClientRect().bottom;//viewport+pos+of+bottom+of+el
++++
++++let+baselineLocator+=+document.createElement("img");+//+needs+to+be+an+inline+element+without+a+baseline+(so+its+bottom+(not+baseline)+is+used+for+alignment)
++++el.appendChild(baselineLocator);

++++baselineLocator.style.verticalAlign+=+'baseline'+;+//+aligns+bottom+of+baselineLocator+with+baseline+of+el
++++let+baseLineY+=+baselineLocator.getBoundingClientRect().bottom;//viewport+pos+of+baseline
++++el.removeChild(baselineLocator);
++++++++
++++return+(bottomY+-+baseLineY)+;++++++++
}

function+positionLine(){
++++let+line+=+document.getElementById("line");
++++let+lorem+=+document.getElementById("lorem");
++++let+baselineHeight+=+getBaselineHeight(lorem);
++++let+newLinePos+=+lorem.getBoundingClientRect().bottom+-+baselineHeight+;
++++line.style.top+=+newLinePos+%2B+"px"+;

}|code-block|syntax|javascript|230649|#lorem{
++++background-color:+lightblue;
}
#line{
++++position:absolute;
++++left+:+0+;
++++height:1px;
++++width:100%25
}|230650|<link+href="https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css"+rel="stylesheet"/>
++++++++<span+id="lorem">Lorem+ipsum+dolor+sit+amet,+consectetur+adipiscing+elit..</span>

++++++++<br><br>

++++++++<button+class="btn+btn-primary"+onclick="positionLine();">position+line+on+baseline</button>

++++++++<br><br>

++++++++<svg+id="line">
++++++++++++<line+x1="0"+y1="0"+x2="100%25"+y2="0"+style="stroke:rgb(255,0,0);stroke-width:1"></line>
++++++++</svg>+|230651|230652|entityMap^0|0|J|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|T|8|@$9|U|A|V|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|W|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|X|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|J|7|Y|8|@]|D|@]|E|$K|L]]|$1|O|3|P|5|J|7|Z|8|@]|D|@]|E|$K|L]]|$1|Q|3|G|5|6|7|10|8|@]|D|@]|E|$]]|$1|R|3|-4|5|6|7|11|8|@]|D|@]|E|$]]]|S|$]]

<p><strong>Vanilla JS, no font info required</strong> tested on Chrome, Firefox and Edge   :</p>

<p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>function getBaselineHeight(el){
    let bottomY = el.getBoundingClientRect().bottom;//viewport pos of bottom of el
    
    let baselineLocator = document.createElement("img"); // needs to be an inline element without a baseline (so its bottom (not baseline) is used for alignment)
    el.appendChild(baselineLocator);

    baselineLocator.style.verticalAlign = 'baseline' ; // aligns bottom of baselineLocator with baseline of el
    let baseLineY = baselineLocator.getBoundingClientRect().bottom;//viewport pos of baseline
    el.removeChild(baselineLocator);
        
    return (bottomY - baseLineY) ;        
}

function positionLine(){
    let line = document.getElementById("line");
    let lorem = document.getElementById("lorem");
    let baselineHeight = getBaselineHeight(lorem);
    let newLinePos = lorem.getBoundingClientRect().bottom - baselineHeight ;
    line.style.top = newLinePos + "px" ;

}</code></pre>
<pre class="snippet-code-css lang-css prettyprint-override"><code>#lorem{
    background-color: lightblue;
}
#line{
    position:absolute;
    left : 0 ;
    height:1px;
    width:100%
}</code></pre>
<pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;link href="https://maxcdn.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css" rel="stylesheet"/&gt;
        &lt;span id="lorem"&gt;Lorem ipsum dolor sit amet, consectetur adipiscing elit..&lt;/span&gt;

        &lt;br&gt;&lt;br&gt;

        &lt;button class="btn btn-primary" onclick="positionLine();"&gt;position line on baseline&lt;/button&gt;

        &lt;br&gt;&lt;br&gt;

        &lt;svg id="line"&gt;
            &lt;line x1="0" y1="0" x2="100%" y2="0" style="stroke:rgb(255,0,0);stroke-width:1"&gt;&lt;/line&gt;
        &lt;/svg&gt; </code></pre>
</div>
</div>
</p>


<p>I'm hoping to be able to find the height of the <a href="http://en.wikipedia.org/wiki/Baseline_%28typography%29" rel="noreferrer">baseline</a> of a piece of text in a div using javascript. </p>

<p>I can't use a predefined font, because many of my users will be using a larger font setting in their browser.</p>

<p>How can I do this in javascript?</p>


How can I get the height of the baseline of a certain font?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我希望能够使用javascript在div中找到一段文本的的高度。我不能使用预定义的字体，因为我的许多用户将在他们的浏览器中使用更大的字体设置。我如何在javascript中做到这一点？

问如何获取某个字体的基线高度？
EN

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问如何获取某个字体的基线高度？EN